1960s, the city of Clerville. The forthcoming visit of heiress Eva Kant, who'll be bringing a famous pink diamond with her, catches the attention of Diabolik, the infallible and elusive thief whose real identity is unknown: while trying to steal the jewel, he finds himself bewitched by Eva's charm, a feeling she may be reciprocating. But the police, led by Inspector Ginko, is rapidly closing in on him....